An endless track chain includes joints between adjacent links for relative rotation between the links as the track chain advances through its closed-loop path. Each joint is lubricated with a lubricant such as oil in a region between the pin and bushing of the joint. One or more seals inhibit ingress of debris into that region, which could otherwise degrade the effectiveness of the joint and, thus, the track chain itself.
Such a seal is often configured as a face seal, loaded onto an end face of the bushing during assembly. However, over time, both the seal and the end face can become worn as well as other components of the track chain, which may result in axial end play, compromising the integrity of the sealing interface between the seal and end face as well as the integrity of the lubricant intended to be protected by the seal.